1. (Field of the Invention)
The present invention relates to a multi-channel system, particularly a multi-channel PCM music broadcasting system wherein a plurality of blocks are time division multiplexed collectively, each block having at least one music channel and having a different operation mode information such as the number of music channels, music signal bandwidth, quantization bit number and the like, the time division multiplexed signal modulates a carrier, and a plurality of time division multiplexed signals each having a frequency shift from the carrier are collectively frequency division multiplexed for transmission.
2. (Description of the Related Art)
Since the frequency bandwidth of a television channel is about 6 MHz, the number of music channels in a multi-channel PCM music broadcasting is limited in transmission using CATV installations now available. Since a multi-channel PCM music signal must be transmitted at higher transmission rate, the occupied bandwidth becomes broad. As above, the frequency bandwidth of a television (TV) channel is not sufficient for transmission of multi-channeled PCM music signals. In view of the above, conventionally, first a few channel music signals within the television bandwidth are time division multiplexed. The time division multiplexed signal modulates a carrier. Several time division multiplexed signals obtained in the similar manner using several TV channels are frequency division multiplexed for transmission.
Therefore, if a music channel is to be tuned at a receiver side, first a corresponding TV channel frequency is selected. Next, a corresponding block among a plurality of blocks is selected. Lastly, the music channel desired to be tuned is selected from the selected block. The above procedure is cumbersome in selecting a desired music channel.
Further, if the operation mode prior to the time division multiplexing is changed, the procedure for selecting a desired music channel becomes more complicated.